Seeds

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Germination

Growing Days

Most seeds go through a dormant period and germinate when conditions are right -- usually in the spring. To grow to maturity, the plant then needs a certain number of days when conditions are favorable. These are called growing days. If the plant doesn't get enough growing days, it will die before flowering or setting fruit.

The main limit on growing days is frost. A plant that is sensitive to frost can't be placed in the garden until after the last frost in the spring, and it will die with the first frost of the fall. Often, there are not enough frost-free days available to grow the plant.

Gardeners get around this problem with seed germination procedures. When you start seeds indoors, you make the growing season longer.

When to Start Seeds Indoors

Seeds are often started in late winter or early spring, but not all seeds should be started at the same time. Some seeds germinate more quickly than others, and some seedlings can be placed in the garden earlier than others. Here's how to plan your seed germination schedule:

Start with the set-out date for the specific plant. Often, this is the last frost date in your locality. Plants that can tolerate mild frosts can be planted in the garden a little earlier, especially if you provide protection on cold nights.

Decide how mature you want your plants to be when you put them in the soil. Flowers in flats at garden centers are often completely mature and flowering freely when you buy them. Slightly younger plants adjust more quickly to their new location and put down roots better. Check how many days the seedling will need to grow from germination to the right size to set out. This information is usually on the seed packet or in the seed catalog.

Some seed germination is quicker than others. Check the average number of days your seeds will need to germinate.

Add together the growing days and the germination days your seed will need. Find your set-out date, and count backwards on the calendar the total number of days you will need to grow the seedlings. That's your sowing date, the day you will start seed germination.

For example: Suppose the last frost in your area usually comes around May 30th. That's your set-out date. You want almost mature plants to put in your garden, and you know this species takes about 60 days to mature. That means you want new seedlings to sprout around April 1st. If these seeds take about 10 days to germinate, you should plant them around March 20th.

What You Will Need

Growing Medium

You will need a sterile growing medium. If you buy soil, be sure the label says it has been sterilized. Some gardeners prefer to use a soilless medium, such as a mix of peat, perlite, and vermiculite, for seed germination.

The biggest problem in starting seeds indoors is damping off of seedlings. Using a sterilized medium minimizes the fungus spores that cause the problem. Providing good drainage and air circulation for the seedlings also reduces damping off.

Container

Seeds can be planted in flats, peat pots, or any of the commercially-available containers you see at the garden center. If these containers have been used the previous year, they should be sterilized before use.

Seeds can also be planted in dixie cups, egg cartons, foil baking tins, or many other convenient objects. Just be sure you have punched plenty of holes to allow for drainage.

Cover

Many seed germination kits come with a clear plastic top. If you are using plain flats or other ordinary objects, you will need to make an airtight cover. Plastic wrap or a large plastic bag will do the job.

Seed

Most gardeners buy fresh seed every year from a commercial company. Many popular flower and vegetable seeds are hybrids, and only grow well if purchased from a seed company.

Heirloom seeds are usually seed from old-fashioned varieties of plants. These plants will grow reliably from seed collected the previous year in your garden.

In either case, fresh seed will germinate more easily than seed that has been stored for several years.

Temperature

Most seeds germinate best when the soil temperature is around 70 degrees Fahrenheit. Some require warmer or cooler temperatures. Decide in advance where you will place the trays to provide the correct temperature. Some garden centers sell special warming devices for this.

Procedure for Seed Germination

Wet the growing medium. It's easiest to do this while it is still in its bag; just cut off the top and stir the medium while adding water. You don't want it to be soaked and dripping, just evenly moist all the way through.

Fill the container with the moist growing medium. It's usually best to add soil right up to the rim.

Plant the seeds. Different seeds require different planting methods. For some, you will need to poke a hole in the medium, insert a single seed, and pat the hole shut. For others, you will sprinkle the seed across the surface of the growing medium. Check the directions on the seed packet.

Cover the seed if necessary. Some seeds need light to germinate, so you should leave them on the surface of the soil. Others require darkness and must be covered. They may germinate best with a deep cover or a very light cover. Many gardeners use lightweight vermiculite to cover seeds.

Water from the bottom by placing your flat or container in a larger container filled with tepid water.

Cover the container, or put it inside a plastic bag and tie the bag shut.

Place the container in the spot you have chosen. Check the seeds daily. When the first two or three seedlings pop out of the soil, remove the plastic cover.

Keep the container in the same spot for another day or two, until most of the seeds have germinated. Don't let the soil dry out.

When most of the seed germination is complete, move the seedlings to a sunny windowsill and watch them grow!

Resources

Seed Balls

Seed Saving

Seed Exchange

Organic/Heirloom Seed Catalogs

GENERAL HARVEST METHODS

    In late summer, I begin checking the garden for signs of seed development.

The withering or dropping of flowers indicates that seeds have begun to form. After that milestone, I watch for flower stalks that have dried and turned brown and seedpods that have turned from green or yellowish brown to brown, gray or black. The vast majority of herb seeds are brown or black when ready to harvest. 

    A reliable test of seed maturity is a light tap on the dry flower stalk.

If any seeds rattle or are dislodged, they are ready for harvest. Also, watch for birds eating the seed heads (as they do reliably on my _Agastache_ plants). This is an obvious indication not only that the seed may be mature (though some birds will eat green seeds) but that you'd better get out there and harvest it. If the seeds are small or contained in pods so that their maturity isn't outwardly visible, as in the sages (_Salvia_spp._) or anise hyssop (_Agastache_foeniculum_), I select a dry, brown flower stalk and remove some of its seeds; if they're dark brown or black, it's time to harvest them. 

    I harvest seeds late in the day after a few days of dry weather to ensure

that all plant parts are dry. If the foliage or seed head is wet when picked, it will not dry quickly and is likely to mold. Few sights are more disappointing than a bag of seed heads that have turned to compost. 

    Cut the entire seed head or part of the flower stalk that contains seeds,

avoiding any part of the plant that is still green, and place it in a large paper bag, cardboard box, or wooden bowl. Place only one kind of seed in each container, and label each with the name of the herb it contains. 

    Occasionally, I come across seed heads that are covered with aphids.  I

harvest them anyway but then place them in the freezer for a few days to kill the aphids. This doesn't seem to harm the viability of the seed.

COLLECTING FROM SPECIFIC PLANTS 

    The first couple of years I grew pink gas plant (_Dictamnus_albus_

'Rubra'), I collected the seedpods in a small, open basket and was mystified when I later found the pods open but no seeds in the basket. I discovered that the seedpods pop open when they dry, and the seeds are expelled forcibly. I now collect gas plant seed when the pods begin to turn brown but before they've opened, and I put them in a closed paper bag. I can hear the seeds as they hit the sides of the bag. Some gardeners collect gas plant seeds by placing a paper bag or a piece of netting or sheer pantyhose over the immature seed heads while they're still on the plant, and attaching it to the stem with a twist tie. 

    The ripe seedpods of butterfly weed (_Asclepias_tuberosa_) split open to

expose great multitudes of seeds lodged in a cottony mass for wind dispersal, much like dandelion seeds. When the first pod on a plant splits open, I harvest all the pods on that plant and, as with gas plant, put them in a closed container. 

    Seeds of many plants, including honeywort (_Cerinthe_spp._) and borage,

mature along the flowering stem until hard frost kills the plant. Borage will easily self-sow, but our winters are too hard for the honeywort, and so after the plant has been in flower for a while, I inspect the lower ends of the flower stalks daily. I pick any mature black nutlets carefully to avoid disturbing the upper end of the stalk, which is still flowering and contains immature seeds.

AFTER-RIPENING AND DRYING 

    Few seeds will germinate if planted immediately after ripening on the

plant. I therefore leave the seed heads I've collected in their containers a few weeks until the seeds have dried and ripened completely. After the seed coat has dried and hardened, the embryo slowly loses moisture and also undergoes chemical and other physiological changes. The seed needs to be kept in a dry, warm place with good air circulation; I prefer the garage, as any hitchhiking insects can escape without entering the house. If you're pressed for time, you can remove the seeds from the dry pods or seed heads and clean them immediately after harvest, but then give them a few weeks of open-air drying before storing them in airtight containers. 

    The main danger in storing seeds in an unheated garage or barn is the high

humidity that several days of rain can produce. Seeds and other plant parts will take up the moisture from the air and thus become more susceptible to disease. By the time the fall rains start (usually in early September in north-western Oregon), I will have taken all my seeds inside the house and started the next tasks: checking them carefully for insects, then cleaning them. 

    The only seeds that I find at all difficult to extract are those of

licorice. The two hard seeds are contained in a small pod that's covered with stiff, fine bristles like tiny slivers. I used to open each pod individually by pressing my thumbnail down on the pod seam, hoping my thumb was callused enough to prevent penetration by a spine. I finally wised up and now place the tough pods between newspapers and walk on them with heavy boots first, which tends to rub off the bristles as well as break open some of the pods. The seeds, dark green when mature, are tough enough to withstand this treatment.

CLEANING 

    Seed is cleaned by separating it from the plant material (chaff) that was

harvested with it. By the time I get around to cleaning my seed, much of it has already separated from the plant in handling and is lying on the bottom of the bag. In other cases, vigorously shaking the dried flower spike will separate the seeds from the plant. Sometimes it may be necessary to "milk" the seeds out with a gentle squeeze at the base of the pod. However, experience has taught me not to try to collect every single seed, just the ones that separate easily from the plant. Those that have been injured or have not fully developed may not separate easily and should be thrown away; the wound that occurs when an under-developed seed separates from the plant can be the first point of entry for fungal infection during storage. 

    Freeing large seeds from the chaff is easy enough; I just pick them out

with a knife or tweezers. I pluck really large seeds, such as those from lovage, angelica, and sweet cicely, directly off the seed heads individually and avoid the issue of cleaning altogether. 

    For small seed, such as that of summer savory, winnowing is the easiest

method for separating the chaff from the seed. There are many ways of doing this and a lot of room for creativity. Each year, we dedicate a board meeting of the Hardy Plant Society of Oregon to seed cleaning for our seed exchange. Members bring an amazing array of aluminum pie plates, knives, clippers, wooden bowls, colanders, cookie sheets, homemade screens and magnifying glasses, and use them in many clever ways to extract the seed from the chaff. Some folks scoop small amounts of round seeds (basil and clary sage) with their chaff onto a tilted cookie sheet; the seeds roll down, and the chaff stays put. Screens can also be helpful in cleaning. Start with a mesh size just large enough to allow the seeds to fall through when they are brushed lightly across the screen, then use a slightly smaller mesh that will hold the seeds but allow smaller material to be brushed through. 

    No matter what ingenuity you bring to the process, though, seed cleaning

can sometimes be tedious. I have no special tools for the job, just a pair of tweezers, lots of patience, and perhaps a captivating television show. I spread newspapers on a table, dump out small amounts of seed, and manually pick out the seeds, throwing the chaff into a bag beside me.

STORAGE 

    The container you choose for storing the cleaned seed should be relatively

airtight. Baby food jars or other small, lidded jars are good for seed storage. I use plastic margarine tubs, and I write the name of the herb and the year on a piece of paper taped to the lid. I leave the lids off for a few days to ensure that any excess moisture is gone, and then I snap the lid on tight. 

    Check stored seeds periodically for mold and insect damage.  Clumping of

seeds when the container is slowly tilted and rotated may indicate mold. Other signs include a black, sooty color and perhaps a moldy smell. If you suspect mold, dump the seeds on a sheet of white paper, then pour them back into their container and look for black, downy dust on the paper. If there is any mold, throw away the entire container of seed. 

    Fine dust at the bottom of a container may indicate the presence of

insects, and further examination is wise. Most storage pests are larvae that are large enough to see without a hand lens, and their webs are usually visible in a container of seed. If you find or suspect an infestation, freeze the seed for a couple of days to kill the insects. Dry ice can also by used to kill insects in stored seed. Simply drop a piece into the container, then replace the lid lightly. The insects either die from the cold or suffocate when the dry ice sublimes into carbon dioxide. CAUTION:: Don't screw the lid tightly on a jar containing dry ice, as the jar will explode. 

     The optimum storage temperature for seeds ranges from 35 deg to 65 deg F,

and humidity should be low. (a refrigerator is an excellent place to store seeds if you have enough space.) Seed stored under these conditions can remain viable for at least 2 and sometimes as long as 15 years, although with every additional year in storage seed viability will decrease. 

    Seeds must never become completely dry: the tissues within the seed must

retain at least a small amount of moisture to remain alive. Some seeds with hard coats are able to withstand dessication to a moisture content as low as 5 per cent of their total weight, while others with fleshy reserves may tolerate dessication only to 60 per cent. Seeds stored in a paper packet take up and lose moisture within a range of 5 to 20 per cent of their total weight in response to the humidity of the surrounding air; seeds in the open air take up and lose moisture even more rapidly. These frequent fluctuations can seriously impair seed viability.

SEED TYPES AND CHARACTERISTICS 

    Most herb seeds are small and dry and have a hard, dark brown or black

seed coat. They typically are long-lived: seeds of sweet basil often are viable for seven years or more under proper storage conditions. Many such seeds, especially those of biennial and perennial herbs, may require a period of cold or of dry storage to induce dormancy before they will germinate. 

    A few herbs, such as angelica, lovage, sweet cicely, and parsely, produce

moist seeds. The seeds tend to be large and have fleshy, spongy inner tissues because of their large storage reserves. Such seeds are short- lived: they tend to dry out over time; this process is accelerated under improper storage. Cold storage in the refrigerator or freezer not only helps maintain the viability of moist seeds but also induces dormancy in those that require it for germination. 

    An ANNUAL herb completes its life cycle in a growing season, which is

typically a year. After flowering and setting seed, the original plant dies. Most annual seeds have no special requirements for germination; once ripe and dry, they will germinate if given sufficient warmth and moisture. 

    A BIENNIAL plant completes its life cycle in two growing seasons or years.

Most biennial herbs belong to the parsley family (Umbelliferae). They include caraway, parsley, and angelica. Such plants should be grown either from fresh seed that has been dried thoroughly and then planted immediately in early fall or from seed that has been stored in the cold to ensure high germination. 

    PERENNIAL plants live for more than two years.  All perennial herbs

produce dry, hard seed except for French taragon, horseradish, and true peppermint, which do not produce viable seed and must be propagated vegetatively. Gardeners may become frustrated trying to propagate perennial herbs from seed because many perennial seeds contain chemical inhibitors, or dormant embryos, or have impermeable seed coats or other characteristics that pervent germination unless the seeds are specially treated.

VIABILITY TESTING 

    I find it fascinating to see a seed develop into a living plant, but it's

extremely frustrating when I plant a large number of seeds and only a few germinate. I try to use my own collected seed as much as possible because I know its history and can attest to its parentage, but often I must rely on commercial seed companies, friends, and seed exchanges through garden societies and botanical gardens (see sidebar "Desperately Seeking Seeds?") In all cases, unless I test the seed for viability, I have no idea whether it is alive, has been properly stored, and has met its dormancy requirements for germination. 

    Testing seed is not hard to do: just take a sample (perhaps two dozen

seeds) and place it on a pad of wet tissue or moistened paper towel in a closed container and see how many germinate, and how quickly. However, not all seeds are alike; germination for some may depend on the presence or absence of light, and the actual spectral quality of the light, and/or the temperature, including the fluctuation between night and day temperatures, and some seeds may require pretreatment in order to germinate.

SCARIFICATION 

    Some seed coats, such as those of hibiscus seeds, are initially almost

impermeable to water or air. To promote germination, you must open or soften the seed coat by either nicking it with a knife or sanding it lightly with a file or sandpaper. Extreme care should be taken to cut through or abrade only the seed coat and not injure the embryo. As soon as the seed coat is penetrated in this way, the embryo is susceptible to fungal infection, and the seed must be planted immediately.

SOAKING 

    The hard seed coats of herbs such as parsley need to be softened to allow

adequate water uptake and air exchange. Placing such seed in hot (not boiling) water and letting it stand for between 6 and 24 hours will help leach out any chemical inhibitors, shortening the germination time. Sow the seed immediately after soaking.

STRATIFICATION 

    In seeds such as those of sea holly (Eryngium spp.), the moist cold of

winter causes physiological changes that are necessary for germination. To mimic this cold period, soak the dry seeds in warm water (170deg-210deg F) for 12 to 24 hours. Sow them immediately into a moist planting medium in an airtight container (I often use resealable freezer bags). Place the container in the refrigerator or freezer for three to five weeks. I put sweet cicely seeds in the fridge and angelica seeds in the freezer, but either fridge or freezer will yield about the same result. Empty film canisters with their tight-fitting lids work very well for stratifying small amounts of seed.

PROPAGATION AND PARENTAGE 

    As a commercial wholesale herb grower, I still regard growing herbs from

seed with mixed emotions. There is no easier way to propagate annual herbs and most biennials. However, continued seed propagation of cultivars or hybrids, if not done selectively, can result in the eventual loss of important genetic qualities of the orginal parents. I recall reading in old herb books about a dwarf purple basil that I believe is now lost, and I know of a commercial grower whose Purple Ruffles basil mostly came up with green spots this year. The popular lavender cultivar Munstead has been propagated by seed for years and is probably far different from the original strain. 

    To maintain the characteristics of the parents, cultivars of perennial

herbs should be vegetatively propagated. Those grown commercially from seed must be selected for varietal characteristics; seedlings that don't measure up should be discarded. Many annuals can be propagated from cuttings, and some growers use this as a means of maintaining a variety. 

    I feel that we, as gardeners, have a responsibility to try to preserve

"old-fashioned" plants, and I applaud seed foundations that are establishing genetic seed banks for heirloom plants in an attempt to perpetuate certain varieties so that we won't be left with an odd lot of hybrid seedlings.

SEED SAVING BASICS

    Begin next year's garden this year by selecting the plants that will

provide your seeds. Pass by the hybrids, no matter how much you may prefer these types of plants. A hybrid is the product of a selective crossing of two (or more) unrelated strains of a plant; say, a variety of tomato that develops a thick, strong stem crossed with a type that produces extra-large fruit. The resulting F1 hybrid, or first-generation cross, will display the best traits of both parent plants. Hybrids are generally more vigorous than either parent, a desirable characteristic. 

    Seeds from these crossbreds, however, will not produce true to type.  The

new plants will "revert" to something like the parents, or possibly like an ancestor of one or both of the parents. In the case of tomatoes, the seed of hybrid fruit often reverts to a cherry tomato-type plant. 

    Instead, save seed only from open pollinated -OP- plant varieties.  The

OPs aren't as common in seed catalogs as they were a decade ago, but they're frequently available in such old favorites as 'Golden Bantam' corn and 'Rutgers' tomato. OP seeds reproduce true to type year after year, given a little help and wise guidance from their gardener. 

    A few OP varieties are self-fertilizing, with individual flowers on the

plant providing their own genetic material. Such plants include beans, lettuce, peas, and tomatoes. This means you can grow several varieties of each - for example, Romano, Kentucky pole, and wax beans - in the same garden, and the plants will not crossbreed. 

    Other common OP plants produce seed through fertilization either by wind

or insects. These include corn, beets, cabbages and other brassicas, carrots, melons, cucumbers, radishes, spinach, squash, pumpkins, and turnips. For such types you have three options to prevent accidental crossing. You can plant only a single representative of the group; you can stagger plantings so that seeds of crossable types mature at different times; or you can hand-pollinate and hand-protect the individual plants that have been selected to produce seeds. 

    There is a fourth option that may appeal to the adventurous; letting

plants of a particular type cross freely. For example, you could plant in proximity two types of cucumber; an eight inch slicing variety and a tiny gherkin. The next year's harvest could be very disappointing, or you could produce a truly desirable new vegetable. 

    Keep only seeds from plants that have done particularly well in your

garden: those that are resistant to local insects and weather conditions and that have the best-tasting fruit. After several years of saving seeds from your own "line", you will have developed plants that are uniquely and individually adapted to your growing methods and region. 

    Store saved seeds in glass jars and keep them in a freezer.  Make labels

for the different seeds, but keep these inside the jars; otherwise, they'll fall off. On the labels include the year of harvest and the specific variety (i.e., 1993 'Longkeeper' tomato) and any interesting traits of growth that might help you in the future. 

    Seeds stored in freezing temperatures should remain viable for several

years. It's not unusual, though, to find that only half a batch of home- collected seeds will grow, so always keep more than you expect to need. It's a good practice to plant at least some of your stored seed every year, to keep supplies fresh. But never plant all the seed of one type; if the crop fails, you won't have any to fall back on. 

    Generally, vegetables are harvested at peak condition; in doing so, the

seeds-to-be -- as fruit -- are removed before they are ready for saving. When saving fruit for seed, you need to allow it to reach its ripest condition before picking it. The optimum conditions for saving the seed of both annuals (plants that produce seed during the first year) and biennials (plants that require two years growth to produce seeds) are given below.

ANNUALS

BEANS: Pick freely from your plants until later in the season (leaving ripe beans on the vines early on may cause production to stop). Let the last pods dry while they're still hanging on the plants. If the weather is too damp and the seeds begin to mildew, pull the entire plants by the roots and hang them upside down in a sheltered area until the pods are completely dry. Crack out the seeds, and store them in glass jars with tight lids. Some folks add a bay leaf per jar to repel bugs.

CORN: Plant only a single variety, or stagger plantings so that the varieties mature at different times. Serious corn growers advocate saving seeds from no less than 100 ears, so that a number of different plants are represented in your genetic seed stocks. But it's better to save seed from just a few ears than to not save any at all. Select only cobs that represent the best or your corn: hardy plants, strong and upright in the wind, ears filled out, little or no insect damage, husky kernels. Let the corn dry in the husk on the plant; bring it indoors before the weather turns damp. Remove the husks and hang the cobs to dry until the kernels are slightly loose. Shell them, and store them.

CANTALOUPES: There are many varieties of these aromatic melons, including the familiar orange-fleshed supermarket type, green-fleshed supermarket type, green-fleshed muskmelons, and even a small, hardy indigenous North American sort called "mango melon" or "vine peach". These all cross freely. (See the section on pumpkins for information on hand-pollination) Select several early fruits to eat from these plants. Remove the seeds, rinse them, and dry them on a plate before storing them.

CUCUMBERS: If you have several plants, save seeds from the first fruit on one and the last fruit from another. If you have just one plant, you'll have to save seed from the last fruits, for if the cukes aren't picked, the plant will stop fruiting. Let a couple of large, healthy cukes remain on the vine until the fruit has turned a golden color. Peel and mash the whole cucumbers. Cover them with water, and let this stand at room temperature for several days; it will become pretty smelly. Pour off the liquid as well as the goo floating in the water. Viable seeds will have settled to the bottom of the container. Spread the seeds on a plate to dry before storing them.

PEAS: Treat the same as beans.

PUMPKINS, and WINTER and SUMMER SQUASH: These all come from four species of the _Cucurbita_ genus. Crossing within species is possible, so you should plant only one variety from each one. _Cucurbita_Pepo_ includes acorn, cocozelle, crookneck, and scallop squash, pumpkins, and zucchini. _C._Maxima_ includes banana, Hubbard, buttercup, and turban squash. _C._Moschata_ covers butternut and "cheese" squash. And _C._Mixta_ includes cushaws. So you could confidently plant an acorn squash, a Hubbard squash, and a butternut squash without any crossing.

Suppose you want to grow pumpkins and zucchini, both members of _C._Pepo_. Then what? You could separate the plantings by several hundred feet, which will slow down pollinating insects. Or you could hand-pollinate female flowers. To do this you detach a male flower (it will have a slender base), and carefully tear away the flower "petals" so that only the long anthers and stem remain. Swab this across the newly opened female flower (with the tiny fruit at the base), to distribute pollen. Use several male flowers on each female. Gently tape the female flower shut, and you're done.

If the _Cucurbita_ species cross and produce fruit, the results will be perfectly edible and often quite interesting.

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